The invention relates to a method for cleaning the filters of a vacuum cleaner comprising a dirt collecting container, which has a suction inlet and is in flow connection with at least one suction unit via at least one filter and at least one suction extraction line, and comprising at least one external air inlet which opens into the suction extraction line downstream of the at least one filter and is adapted to be closed by means of at least one closing valve, wherein the at least one closing valve has a valve body which is movable back and forth between a closed position, in which it lies against a valve seat, and an open position, in which it is at a distance from the valve seat, wherein it is acted upon by a closing spring with a closing force and, in the closed position, additionally by a magnetic holder with a magnetic holding force, wherein, in order to clean the at least one filter, at least one closing valve is opened and the side of the at least one filter that is oriented away from the dirt collecting container is impinged upon by external air.
The invention also relates to a vacuum cleaner for carrying out the method.
By means of the vacuum cleaners in question here, dirt and preferably also liquid can be sucked up using at least one suction unit to apply negative pressure to the dirt collecting container, so that a suction flow forms and dirt and liquid can be sucked into the dirt collecting container. The vacuum cleaners have one or more filters, which are disposed in the flow path between the dirt collecting container and the at least one suction unit and serve for separating solid substances from the suction flow. During suction operation, dirt particles are increasingly deposited on the side of the at least one filter that is oriented toward the dirt collecting container, so that after some time the filter or filters have to be cleaned. For cleaning, the side of the filters that is oriented away from the dirt collecting container can be impinged upon by external air, by opening at least one closing valve, so that external air can flow into the at least one suction extraction line via the external air inlet and impinge upon the side of the at least one filter that is orientated away from the dirt collecting container.
In utility model DE 298 23 411 U1, to clean a filter it is proposed to close for a short time a suction hose that is connected to the suction inlet of the dirt collecting container, so that a strong negative pressure forms in the dirt collecting container, and a closing valve is subsequently to be opened for a short time. The filter is then flowed through by the external air in the direction of counterflow, that is to say counter to the direction of the suction flow that prevails during normal suction operation, so that dirt particles adhering to the filter become detached.
In DE 199 49 095 A1, it is proposed to use two filters, which are cleaned in turn, it being possible during the cleaning of one filter for the suction operation to be continued to a restricted extent by way of the other filter.
JP-A-2002028107 discloses a method for cleaning a filter in which the filter can be flowed through by external air counter to the direction of flow prevailing during normal suction operation. Provided for this purpose is an external air inlet, which is adapted to be closed by a valve. When the valve is opened, external air is sucked in on account of the pressure difference between the pressure in the dirt collecting container and the pressure in the outside ambience. This difference in pressure is also present when the suction operation is stopped.
It is an object of the present invention to develop a method of the generic type in such a way that particularly effective cleaning of the at least one filter is made possible.